1. Field of the Invention
The present invention is in the field of mechanical dryer utilities and pertains particularly to configurations providing secondary filters including lint traps used in clothes dryer systems.
2. Discussion of the State of the Art
Contemporary clothes dryer systems are well known in the art and generally embody a cabinet type utility having a front wall, rear wall, opposing sidewalls, top wall, and, optionally, a bottom wall. Clothes dryers are available in electrical models, in which heat is generated via a resistance element or via a “heat pump” method. Clothes dryers are also available such that heat is generated by a gas combustion chamber. In either case, a drum is typically provided for containing the clothes to be dried. In process, the drum containing clothes to be dried is rotated, and heated air is either forced into the drum or drawn out through the drum. The heated air passing though the clothes in the drum carries water in the clothes to an external exhaust vent. Heated air typically is passed through an existing lint filter at or near its egress within the clothes dryer. The exhaust then travels through a vent to the open air. The existing lint filter traps lint and particulate created during drying to prevent or reduce lint and particulate buildup of those in the egress path to the vent.
A conduit, typically made of sheet metal, is attached to the clothes dryer to route the exhaust air after it passes though the existing filter to the exhaust vent. The clothes dryer conduit exits the cabinet walls from either the rear or the side of the dryer cabinet, as provided by the dryer manufacturer. The physical space allocated for the clothes dryer often restricts the placement of the exhaust conduit.
The clothes dryer conduit is conventionally attached to a flexible extension conduit, which then may be attached to a vent, or, alternatively, the flexible extension conduit may be attached to a fixed extension conduit and ultimately to the exhaust vent. Sometimes the extension conduit is routed in a way to make it unobtrusive, and, as a consequence, difficult to access. For example, the extension conduit may be routed between an inner and outer wall of a house to the roof or other convenient vent location. It may also be routed under a sub floor to a crawl space to an appropriate exhaust wall. It may also be routed within a concrete sub floor or slab. The extension conduit may make turns, such as 90 degree turns, on its routing to the vent. Typically, the extension conduit is 20 feet or less in length.
The existing traditional lint filter traps lint and other particulate material present in the exhaust air in order to keep the extension conduit clean. Since lint and other materials are typically moist, those that escape the filter have a tendency to adhere to the walls of the extension conduit. Over time the extension conduit may eventually become clogged. Flexible conduit is corrugated and is particularly prone to lint buildup. As is generally accepted in the art, a build-up of lint and/or other particulate material in the extension conduit not only decreases the efficiency of the clothes dryer by reducing moist air flow, it also can sufficiently interrupt the air flow such that the heat and heated air, alone or in combination with built-up lint, becomes a fire hazard.
Existing lint filters are typically constructed of fine mesh material or metallic screen, and may be made of synthetic material, such as a nylon mesh. Due to the fineness of the mesh and of the material, these lint filters may eventually become perforated during manual lint removal and these lint filters can become perforated or destroyed. Traditional lint filters typically are easily removable for cleaning, and sometimes are not replaced when the dryer is operated. Furthermore, although the existing lint filter removes much of the lint and other material in moist exhaust air, it does not remove all of it. Over time, substantial buildup of lint and other material may clog the extension conduit causing interrupted airflow, poor drying efficiency, or even a fire.
The inventor is aware of the existence of secondary “outboard” lint filters known in the art. These “outboard” lint filters are box-type filters which may be added between the clothes dryer conduit and the flexible extension conduit, or, alternatively, between the flexible clothes dryer conduit and the exhaust vent. One such filter is referenced herein as U.S. Pat. No. 5,675,908 entitled “Clothes Dryer Lint Receptacle” invented by Paul S. Barnes and referred to hereinafter simply as Barnes. Barnes describes an externally mounted lint filter receptacle formed as an enclosure that may be mounted to a wall to which an exhaust hose from a clothes dryer may be attached. A screen mesh is provided within the enclosure to remove lint and particulate from exhaust air before it is vented to the outside.
One problem with the receptacle of Barnes is that the area of filtration is much larger than the standard inside diameter of the hose causing an interruption or a weakening in airflow in the exhaust system. Another problem with the receptacle of Barnes is that is requires physically mounting the receptacle to a wall through which an egress path is planned. Barnes also brings to light several other references to U.S. patents that employ some type of filtering scheme for exhaust air emanating from a dryer however, all of those devices are complex with more than one moving part, and must be assembled, or otherwise require much work and attention to operate correctly. Likewise, all but one of those inventions filters air for release internally to the building area hosting the clothes dryer. Further problems exist in that the receptacle of Barnes and those systems referenced by Barnes are not installable in a fashion that might be convenient for a user given the typically restricted space between the back wall of clothes dryer and the opposing house or building wall that the dryer is positioned in front of.
Therefore, what is clearly needed is an integral lint filter for a clothes drying system that may be conveniently installed between the exhaust port on the dryer and an exhaust conduit or hose without requiring much installation work, and that may be simply removed for cleaning and replaced for further use.